Now, imagine this. What if this guy just started exaggerating his story of survival when he told it to other people? What if this story was told over and over again by many different people over generations? What if the people retelling this story all added an extra detail of their own to make it more interesting?
Especially if it was after a crazy catastrophic flood like the flooding of the Black Sea. A kind of flood that was different from the river floods. Something where a natural dam broken which looks kinda like "fountains of the deep".
Of course, biblical creationists are committed to belief in God's written Word, the Bible, which forbids bearing false witness; --AIG (lest they forget)